Hello, I noticed some odd behaviour with list comprehensions. [1..1] == [1] BUT [1,1..1] == [1..] I noticed this while writing a Clean program, but it seems Haskell inherited this as well. In the case of integer lists with step size >= 0 the up_list function[1] is used: up_list :: Integer -> Integer -> Integer -> [Integer] up_list x0 delta lim = go (x0 :: Integer) where go x | x > lim = [] | otherwise = x : go (x+delta) In the case of [1,1..1] x0 == lim, so go will recurse infinitely, producing an infinite list. I think the reasonable behaviour would be [1,1..1] == [1]. Is there a reason it doesn't work like this? [1] http://hackage.haskell.org/package/base-4.8.2.0/docs/src/GHC.Enum.html#up_li... Thanks, Krisztián